The invention relates to a navigational system connected to a centralized server and, more specifically, to the improvements required to convert a terminal (for instance a radiotelephone or an electronic organizer) into a navigational aid system, particularly for automotive vehicles.
Over the years, different types of navigational aid systems and of data access have been developed particularly for automotive vehicles. These systems make the driver""s work easier by calculating the best itinerary (the shortest, fastest, simplest, or least expensive, etc.) to reach his destination and thereby spare him the trouble of reading a map while driving. These systems are particularly useful when driving in unfamiliar areas or for choosing the shortest course considering real-time road conditions (road works, traffic, demonstrations, weather, etc.).
Earlier state-of-the-art includes systems with integrated large screens which make it easier to read maps in vehicle integrated terminals dedicated to automotive navigation.
These expensive devices have the capability to calculate the position of the vehicle so as to display it on a road map. The position of the vehicle can be determined with the aid of satellite signals receivers (the GPS, for example) or inertial or else by triangulation of the signals emanating from ground stations (for example the base stations of a mobile telephone system such as GSM).
Calculation of the position of a GPS receiver for example, is based on the position data provided by three or more satellites and the delay of transmittance of these signals to the receiver. However, the accuracy of such systems is limited to about 100 meters, due partly to natural causes (weather variations, changes in the ionosphere, reflection on obstacles, etc.), and partly to deviations introduced deliberately on the signals for the civil use of systems such as the GPS managed by the US Defense Department. To make up for this lack of accuracy, earlier state-of-the-art describes the use of differential GPS receivers, expensive devices that include an extra decoder, of the radio or satellite type, to pick up signals providing corrective values, measured by a fixed station that compares the real position of the station to the position obtained from the satellite signals. In order to optimize real-time calculation of the itineraries, these navigational systems are sometimes equipped with receivers picking up information on traffic conditions, for example the RDS system. These receivers further increase the cost of the in-car terminal.
To make driving easier and safe for the driver, the systems are sometimes fitted out with voice recognition systems and/or with a voice synthesis system which further complexify the navigational systems since a microphone, a loudspeaker and at least one processor need to be added to carry out voice recognition or synthesis or both. In all cases, real-time voice recognition and synthesis are carried out locally. Most often, the processing capability and limited memory of the in-car systems allow for the recognition of isolated words only.
Finally, the cartographic data, which are essential for calculating itineraries and for displaying the position of the vehicle, are generally stored locally, for example on CD-ROM, with the disadvantages of a difficult updating and an increase in the cost, size and manageability of the navigational system.
To offset such disadvantages, earlier state-of-the-art has systems describing the partial use of a central cartographic data base linked by radio to the vehicle.
Some systems advocate complete transmittance of the cartographic data, which requires a very wide band or else imposes very long transmittance periods, given that data transfer on the GSM network is presently done at 9,6 kbits/s.
Other systems propose transferring part of the data at the beginning, then on a regular basis according to the position of the terminal. This limits real-time usage of the data (calculating the length of the journey, the distance to be covered, complete visual display of the itinerary).
Other partial systems propose transmitting only the itinerary and the length of the journey, calculated by the central with eventual graphic elements for the display of intersections. Such systems are of little value in real-time, and the guidance is inadequate, particularly because diversions (blocked roads, missed exits, etc.), some of the most stressful events for a driver, are impossible to manage.
To allow for real in-car guidance, in particular with the aid of a portable telephone, systems using a central data cartographic base are therefore lacking in the means by which the navigational system could guide the driver even if he deviated from the route as first planned, for instance in the case of road works, blocked streets, traffic slowdowns or any other hitches or errors due to absent-mindedness. So, in the present state-of-the-art, either the complete data of the areas through which the driver journeys are transmitted to the terminal for local calculation, or the driver has to query the server again, with all the ensuing delays, if only for the initial time required to establish a new connection.
Also missing in the systems using a centralized data base described above are the means by which the driver could visualize his position in connection with general geographic landmarks without, in the process, overloading transmittance by sending details irrelevant to his itinerary.
Also missing are the means which would provide the driver, in real-time, in text, graphic or voice form, with the directions to follow at every crossroads; the means allowing the driver to give his order verbally without a voice recognition system; the means allowing the navigational system to calculate locally and in real-time the estimated length of the journey and time of arrival; the means to obtain the exact position of the vehicle without using additional radio receivers or satellites for the pick-up of the differential signals; the means to optimize the itinerary in real-time without using any additional radio receivers or satellites for the pick-up of traffic data.
Finally, earlier state-of-the-art navigational systems are lacking in the devices required for converting a portable telephone or an electronic organizer into a real and complete navigational system.
The invention relates to a navigational system to be applied to automotive vehicles for example, including a terminal equipped with the means of communication giving it access to a centralized server through radio relay, satellite or ground link, for example GSM, PCS, CDPD, SMS, PHS, CDMA, GMPCS. The server contains cartographic data and is capable of calculating itineraries. The server does not necessarily possess itself the means of communication but can be linked, for example through Internet, to a gateway towards the radio relay network.
The mobile terminal includes the means to choose start and destination points, to transmit a request including these points, and to ask the centralized server to calculate the best itinerary according to criteria selected by the user (the fastest, simplest, least expensive, shortest, with or without highways, the most pleasant, going through such or such intermediary points, by foot, on a bicycle, by metro, in a bus, etc).
The terminal also includes the means to determine automatically the position of the vehicle, either by using a satellite locating system of the GPS type or an equivalent, or by using the base station triangulation system of a cellular telephony network, or through any other method.
The start position which is part of the itinerary request is preferably that of the vehicle as determined in an automatic manner; entering the start address by hand is thus bypassed.
The invention is characterized by the fact that the centralized server transmits the itinerary in vector form, that is, straight line and arc segments, including, for each segment, at least the latitude and longitude coordinates of its extremities (or of at least one, since the other one can be determined by checking where begins the next segment), thereby allowing a local graphic yield and the positioning of the terminal on the itinerary and eventually the type of road (street, boulevard, national, highway, etc), which in turn makes the transmission of messages easier. The server also transmits typical information for that type of road, the average speed expected on the road, if different from the normalized speed for that type of road, thereby allowing the mobile terminal to estimate in real-time the length of the rest of the journey, and the name of the road, thus making it possible to transmit suitable messages. Other information may also be transmitted, such as which way the street runs, the height allowable on the streets, etc.
The invention is further characterized by the fact that the navigational system includes in the vehicle itself the means by which to pick up this information and to store it, the means to obtain on a regular basis the position of the vehicle, to display the position of the vehicle on a map, on the base of the received segments, to calculate in real-time the estimated time of arrival, to transmit guidance or information messages relevant to the position, in text, graphic or sound form. Thus, a few seconds before a change of direction (according to a programmable delay), the mobile terminal can transmit messages such as: xe2x80x9ctake the second to the right, Montrouge streetxe2x80x9d, xe2x80x9cin 2 km, take exit 106, towards Eastmanxe2x80x9d, etc.
The invention is also characterized by the fact that in addition to the itinerary, the server transmits to the terminal the route segments crossing the itinerary, as well as, if possible, the type of priority of each of the crossroads (stop, lights, priority to the right, etc.) plus, if possible and when required, data allowing identification of the destination to which the intersection leads (for instance, the name of the main towns/cities to which the road leads).
The invention is also characterized by the fact that the centralized service estimates the possibility of the vehicle deviating from its course and taking one or the other of the crossroads. For one, several or each of the possible deviations, the centralized service calculates and also transmits to the terminal the best alternative itinerary for the driver to follow in order to reach his destination, thus establishing an area of proximity information around the itinerary. According to a programmable parameter, the process can be repeated so as to provide a third, fourth, etc level of itinerary in case the vehicle deviates from one of the recommendations of the preceding level.
The invention is further characterized by the fact that the navigational system includes, inside the vehicle, the means required to verify the position of the vehicle compared to the planned itinerary, to determine if the vehicle has taken one of the intersections instead of the recommended course and, in that case, to advise the driver that the precalculated secondary route is now used, if one is available, and to give instructions based on this secondary route.
If a secondary itinerary is not available, or if the vehicle deviates from the new recommended itinerary, or for each level of pre-stored itinerary, one of the third (or umpteenth) levels of transmitted itineraries, then the mobile terminal, after informing the driver, contacts the centralized server automatically and transmits the position, asking the server for a new itinerary to reach the original destination.
There are multiple advantages to the transfer of information on which crossroads and itineraries to follow in case of deviations or driving errors. Among other things, no program of local calculation of itinerary is required, thereby simplifying the in-car guidance program; also, the degree of capability required for processing and memory is lower, plus it reduces the cost of the mobile terminal. This allows an enriched visual display by indicating crossroads and nearby roads, it makes it possible to recommend immediately and without delay a new itinerary in the case of deviations, to display at all times a graphic representation of alternative routes according to the position of the terminal, thereby making it possible to estimate autonomously and rapidly the impact of detouring, for instance to drive by an incident (slowdown, accident, blocked road, etc).
The invention is also characterized by the fact that the server can save the information (itinerary, proximity area, etc) transmitted to the mobile terminal, that it can obtain information regularly on road conditions (traffic, demonstrations, road works) and/or weather conditions, that it can verify regularly if the information affects the itinerary or its proximity area and, if it does, to transmit this information to the mobile terminal and, if useful, for instance when a traffic jam can be bypassed, it can also transmit a new itinerary to the mobile terminal, which then informs the driver of the change and guides him through the deviation.
The advantage is that no additional receiver for the pick-up of traffic information is required in the vehicle, thereby reducing the cost of the in-car system. If the mobile terminal transmits its position to the server at regular intervals, the server will take this into account to verify if a traffic or weather incident is really relevant before advising the mobile terminal. The server can also consult the mobile terminal on its position so as to verify if the changes are important before transmitting this new information.
The mobile terminal can also be equipped with traffic data receivers and, on its own, make the necessary adjustments to allow a new estimation of the length of the journey and also verify if any of the deviations of its proximity area are more advantageous. It can also ask the server if there is a new and more advantageous itinerary given these new real-time weather conditions.
The invention is further characterized by the fact that the server can have in stock or be linked to other servers which have in stock, display data, for instance stills or video images of crossroads, or information allowing the tridimensional projection of the view a driver following the indicated itinerary would have of a crossroads, by the fact that the server transmits the information to the terminal, where they are stored, and by the fact that the mobile terminal can present the displays at the appropriate time according to its position. This is particularly useful in case of doubt, or of errors in estimating the position and, in particular, at crossroads or traffic circles where, 3, 4 or 5 roads cross each other.
The invention is further characterized by the fact that the server can have a database or be connected to other servers with a database holding general information relevant to the itinerary, such as gas stations, restaurants, hotels, tourist, historical or geographic information. The server can transmit this information to the mobile terminal when the itinerary is requested or on request during the journey.
The invention is further characterized by the fact that the driver""s real-time information or guidance messages can be done in audio form. The advantage is that it makes the driver""s work easier, thus making navigation safer because the driver is not required to keep a constant eye on the terminal screen. It also allows the use of a terminal with limited display capacities, for example a GSM phone with a 4 line screen or even an accessory without any display function, for example a telephone accessory such as a hands-free kit for mobile telephones, the processing being done not in the telephone itself but in the accessory to which the telephone is grafted, the telephone then being used solely as a communication module.
These sound messages can be generated by the server according to the itinerary or the position of the terminal, be transmitted to the mobile terminal, either at the time of the initial request or during the journey, be stored by the latter and, as is or in a combination, be played back at the appropriate time by the mobile terminal according to its position. The advantage is that it reduces the complexity and cost of the mobile terminal and also that the choice of language and the ergonomics of the dialogue are not frozen within the mobile terminal.
These messages can also originate locally from a speech synthesis system, at the appropriate time according to its position. This has the advantage of reducing the amount of information the server transmits, but a voice synthesis system is required.
The invention is further characterized by the fact that the requests can be done in voice form. The advantage is that it allows a safer interface because it is less dangerous for the drivers who need to focus their attention on driving and keep their eyes on the road. This also makes it possible to control or consult the navigational system without having to stop the vehicle. Thus, while driving, information such as the remaining distance or time, the distance to the nearest gas stations, hotels or restaurants, or a description of the surrounding tourist area (such as xe2x80x9cwhat is that castle on the right?xe2x80x9d) etc, can be obtained.
So, the mobile terminal digitizes voice and extracts parameters from it for analysis, after which the mobile terminal transmits the parameters to the server, in general along with its position. The server then proceeds with the recognition, searching with the aid of a word list or phonemes bank, determines the object of the consultation and then transmits its answer to the mobile terminal.
Local digitization and extraction of the analysis of parameters provide a sampling covering an important part of the frequencies of the human voice (a sampling at the Nyquist frequency of 44 kHz for example). By analyzing and extracting the parameters before transmittance to the server, one avoids speech distortions caused by the reduced bandwidth of the telephone channels (generally limited to 4 kHz) and by the speech compressions effective in digital telephony (the Full Rate or Enhanced Full Rate coding, for example), distortions which make centralized voice recognition difficult to execute.
So, speaker-independent recognition of natural language becomes possible (rather than the recognition of isolated words from a speaker-dependent), the size of the vocabulary can also be larger and the centralized recognition system can possess a level of memory and a calculation capability that would be too prohibitive for installation in a vehicle. This is particularly important for automotive navigation where the number of cities, streets, etc is generally higher than the size of the vocabularies that can be processed locally. Multilingual and speaker-independent recognition then becomes feasible.
The advantage of transmitting all at once the analysis of the parameters and the position of the mobile terminal is that it totally frees the navigational system user (the driver) and makes his or her task easier. The risks of errors in the voice recognition system are also lower since only one request can be made at a time, thereby reducing the risks of stress and danger for the user at the wheel and allowing the supply of information related to the immediate position.
Of course, voice recognition can also be done locally, with the advantage that it limits the amount of information exchanged between the server and the mobile terminal, but a more complex mobile terminal is required and limits are imposed on the performance of the voice recognition system.
The mobile terminal can use a satellites positioning system, of the GPS type, for example.
The accuracy of the position measured locally by the mobile terminal with the aid of signals picked-up simultaneously from the satellites of a positioning system by satellites of the GPS type can be improved by using differential information, obtained from one or several fixed stations, whose position is known, picking-up simultaneously the signals of the same satellites. Generally, differential information comprise the distance measured (called pseudo-range) between the receiver of the fixed station and each of the satellites, and the real distance calculated from the known position of the fixed station. The increased precision is due to the fact that over a distance of about 500 km, the errors of a positioning system of the GPS type are very similar.
The invention is characterized by the fact that differential information is transmitted by using the same radio relay network used for itinerary requests and answers. That way, there is no need to use another receiver (satellites, RDSIFM, etc) to pick-up differential information, thereby reducing the complexity and cost of the mobile terminal.
The network is preferably of the GSM type, or of the GMPCS (Global Mobile Personal Communications by Satellite) and, preferably, supports the transmittance of short messages of the SMS type.
The invention is also characterized by the fact that differential information can be transmitted by SMS from the server to the mobile terminal, at regular intervals, for instance every 10 or 30 s. The advantage of using short messages of the SMS type is that they can be transmitted even when the radio link is being used during a telecommunication, which makes it easier to use the same network for the transmittance of differential requests, answers, corrections and avoids the use of a device dedicated to the sole reception of differential information.
The invention is further characterized by the fact that the server can be an Internet server which makes its use possible on a world-wide basis, since access to Internet is available throughout the world. The mode of connection being standardized, the use of several types of terminal is also possible. Furthermore, one can take advantage of the fact that several services which can be useful for people on the go are or will be available on Internet, of the fact that the server will be able to access them after an agreement with the supplier of this information, and that it will be possible to select the data while considering the position of the terminal. That way, all the data are not necessarily managed nor stored by the server.
The invention is further characterized by the fact that the vehicle can transfer its position to the server on a regular basis, that these positions can be stored by the server, and that the server can provide one or several third party terminals, including mobile ones, and in particular through Internet, with information on the position of the mobile terminal, at all times. This is particularly useful for locating the vehicle and for fleet management, making it possible to offer both navigational aid and fleet management services, to offer the services by sharing cartographic data with several companies which then do not need to each have their own complete system of fleet follow-up and management. Other information can be exchanged, such as messages, the condition of the vehicle, the length of the journey, speed, weather, the number of turns per minute, the distance already traveled, etc.
Preferably, the information supplied by the server to the third party terminal contains cartographic data in vectorial form corresponding to at least one position of the mobile terminal and includes a program for the display of this information by the third party terminal (a Java program, for example).
The invention is further characterized by the fact that the server can receive requests for calculating itineraries from another terminal (mobile or not) and transfer the itineraries requested to the mobile terminal (and eventual further messages). This allows several alternative ways of implementing the service. For instance, a person can make a connection through Internet or Minitel from his or her house or any other place, request an itinerary, provide the number of his or her portable telephone; the server will then transfer the appropriate itinerary and data to the telephone. Requests can also be made by telephone to an operator who consults the server and transfers the itinerary to a mobile terminal, for example a terminal installed in a vehicle. Among other things, this makes it possible to use as a mobile terminal a portable telephone with a limited keyboard, on which entering an address would be rather fastidious. It also makes it possible to make voice requests about itineraries while at the wheel of a car and allows usage even while driving, which is safer and does not require a voice recognition system.
The invention is further characterized by the fact that the programs of the mobile terminal (extraction of parameters for analysis, real-time guidance, graphic display, etc.) can be telecharged from the server to be stored and executed locally. This offers the advantage of a quick update of the programs when new functionalities become available or to correct errors. Another advantage is that it makes it possible for several types of terminals to act as navigational aid systems. It also allows the use of terminals with more limited storage capacities, the programs being transferred only when required.
The invention is characterized by the fact that a mobile telephone or an electronic organizer can function as mobile terminal for the navigational aid system. Using a telephone or an electronic organizer has the advantage of limiting the number of devices in a vehicle and also of using a device that can be carried everywhere and employed for other functions, rather than a single device dedicated to automotive navigation. Its modulability makes it possible to separate it from other components, for instance, analog-to-digital converter, voice recognition, synthesis, loudspeaker, remote microphone, etc. For instance, the map display function could prove very useful for pedestrians, with or without integrating the sensor of a positioning system of the GPS type. The other interesting aspect of using a telephone or an electronic organizer detachable from the other components, including eventually the receiver of the GPS type, is that it is then possible for the driver to consult the server and to plan his trip from outside his vehicle, and eventually to inquire about road conditions before actually sitting behind the wheel. Once connected to a positioning receiver by satellite in the vehicle, the telephone and electronic organizer can guide the driver during the complete itinerary. Moreover, using a portable telephone is an advantage because the owner of the telephone will be likely to buy a hands-free kit with an integrated receiver of the GPS type. Another advantage of using a portable telephone is that it comes with an integrated screen and keyboard (or touch screen or light pen) and that it possesses the communications components required for implementing this navigational system. Thus, no other screen is required, nor any other communications module (not for request, nor for answers, nor for differential information). This also allows the use of a radiotelephone network, for instance short messages of the SMS type, accessible almost everywhere (and soon, with the satellites networks, everywhere), and then not having to depend on transmitting sources of the RDS type using a FM band.
In cases where the mobile terminal comprises a portable telephone, it is possible either to calculate the analysis parameters directly inside the telephone, or from outside the telephone and, in this latter case, to use the telephone as a communications module. The advantages of calculating the parameters in the hands-free kit are that, often, it already includes a microphone and a processing unit. That way also, a telephone that has not been modified at all can be used.
So it is possible to have a 100% voice solution by using a telephone that has not been modified at all, all the guidance and requests being made by voice.
The totality of the programs required for the navigational aid system described above can also be integrated and executed either on the telephone or the organizer, either in the hands-free kit or any other accessory connected to the telephone.
Other characteristics and advantages of the invention will become apparent from the following description, done for illustrative purposes only and not in the least limiting, referring to the figures hereby appended on which: